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The hemoglobin gene 1 (dmeglob1) of the fruit fly Drosophila melanogaster is expressed in the tracheal system and fat body, and has been implicated in hypoxia resistance. Here we investigate the expression levels of dmeglob1 and lactate dehydrogenase (a positive control) in embryos, third instar larvae and adult flies under various regimes of hypoxia and hyperoxia. | ễFEBS Journal Characterization of L-aspartate oxidase and quinolinate synthase from Bacillus subtilis Ilaria Marinoni1 Simona Nonnis2 Carmine Monteferrante1 Peter Heathcote3 Elisabeth Hartig4 Lars H. Bottger5 Alfred X. Trautwein5 Armando Negri2 Alessandra M. Albertini1 and Gabriella Tedeschi2 1 Department of Genetics and Microbiology University of Pavia Italy 2 D.I.P.A.V. Section of Biochemistry University of Milano Italy 3 Schoolof Biologicaland ChemicalSciences Queen Mary College University of London UK 4 Institute of Microbiology TechnicalUniversity of Braunschweig Germany 5 Institute of Physics University of Lubeck Germany Keywords L-aspartate oxidase NAD biosynthesis NadA NadB quinolinate synthase Correspondence G. Tedeschi D.I.P.A.V. Section of Biochemistry University of Milano Via Celoria 10 20133 Milano Italy. Fax 39 02 50318123 Tel 39 02 50318127 E-mail gabriella.tedeschi@unimi.it Received 4 July 2008 revised 1 August 2008 accepted 12 August 2008 doi 10.1111 j.1742-4658.2008.06641.x NAD is an important cofactor and essential molecule in all living organisms. In many eubacteria including several pathogens the first two steps in the de novo synthesis of NAD are catalyzed by L-aspartate oxidase NadB and quinolinate synthase NadA . Despite the important role played by these two enzymes in NAD metabolism many of their biochemical and structural properties are still largely unknown. In the present study we cloned overexpressed and characterized NadA and NadB from Bacillus subtilis one of the best studied bacteria and a model organism for low-GC Gram-positive bacteria. Our data demonstrated that NadA from B. subtilis possesses a 4Fe-4S 2 cluster and we also identified the cysteine residues involved in the cluster binding. The 4Fe-4S 2 cluster is coordinated by three cysteine residues Cys110 Cys230 and Cys320 that are conserved in all the NadA sequences reported so far suggesting a new non-canonical binding motif that on the basis of sequence alignment studies may
